金融学（第四版）课件：Aggregate Demand and Aggregate Supply

AggregateDemandandAggregateSupply

2AggregateDemandAggregatedemandisthequantityofrealgoodsandservicesthatwillbedemandedatvariouspricelevelsoveraspecifictimeperiodaggregatedemand=consumption+investment+government+netexports3AggregateDemandConsumptiondemandoriginateswiththehouseholdsectordirectlyrelatedtoincomeandinverselyrelatedtointerestratesInvestmentemanatesfromthebusinessandhouseholdsectorsdirectlyrelatedtoincomeandinverselyrelatedtotheinterestrate4AggregateDemandGovernmentdemandincludesonlypurchasesofgoodsandservicestransferpaymentsarenotincludeddeterminedbycomplexpoliticaldecision-makingprocessthatincludesbothCongressandthePresident5AggregateDemandNetexportsarethedifferencebetweenexportsandimportsinverselyrelatedtotheexchangerateandtocapitalinflows6TheAggregateDemandCurveThereisaninverserelationshipbetweentheaggregatequantityofrealgoodsandservicesdemandedandtheoverallpricelevel7TheAggregateDemandCurveRealGDP(inBillions)PriceIndexAggregateDemandOverallPriceLevel(InBillions)0.95$1,7001.001,5001.051,300$1,300$1,500$1,7001.051.00.95AD8TheAggregateDemandCurveAlongaparticularaggregatedemandcurve,allfactorsbesidesthepricelevelandthequantityofrealgoodsandservicesdemandedareheldconstantincluding:thenominalmoneysupplyexpectationsaboutfutureeconomicconditionsinterestratestaxesgovernmentpurchases9TheAggregateDemandCurveTherearethreereasonswhyeconomistsbelievethataggregatedemandisdownwardslopingwealth(realbalances)effectsubstitution-of-foreigngoodseffectconstant-nominal-incomeeffect10TheWealth(RealBalances)EffectWhentheoverallpricelevelchangesforagivenmoneysupply,thesupplyofrealmoneybalanceschangesspendingunitswillexperienceachangeinwealthThisleadstoaninverserelationshipbetweenthepricelevelandrealGDP11TheSubstitution-of-Foreign-GoodsEffectWhentheoverallpricelevelchanges,domesticgoodsandservicesbecomerelativelymoreorlessexpensivethanforeigngoodsthiscanleadtochangesinnetexportsThus,thereisaninverserelationshipbetweenthedomesticpricelevelandtheaggregatequantityofrealGDPdemanded12TheConstantNominal

IncomeEffectBytheequationofexchange,nominalincomeisequaltotheoverallpricelevelmultipliedbyrealGDPwhenthepricelevelchanges,itwillhaveaninverseeffectontheaggregatequantitydemandedofrealGDP13WhytheAggregateDemandCurveSlopesDownwardPriceIndexRealGDP1.TheWealthorRealBalancesEffect2.TheSubstitute-of-Foreign-GoodsEffect3.TheConstantNominalIncomeEffect14TheAggregateDemandCurveWhenaggregatedemandchanges,theentiresetofrelationshipsbetweenthevariouspricelevelsandthequantitiesdemandedatthosepriceschangesTheentireaggregatedemandcurveshiftsifaggregatedemandrises,theaggregatedemandcurveshiftstotherightifaggregatedemandfalls,theaggregatedemandcurveshiftstotheleft15AShiftintheAggregate

DemandCurvePriceIndexRealGDP(inBillions)$1,5001.0AADAD'A'$2,00016WhatCausesAggregateDemandtoChange?Aggregatedemandchangeswhenanyofitscomponentschangesduetochangesintaxesgovernmentspendingthemoneysupplyinterestratesexpectedinflationtheeconomicoutlookexchangerates17WhatCausesAggregateDemandtoChange?Monetaryandfiscalpoliciescananddocauseaggregatedemandtofluctuatethereforethesepoliciesalsoaffectthefinancialsystem(throughinterestratesandstockprices),internationalcompetitiveness(throughtheexchangerate),income,andexpectationsoffutureeconomicandfinancialdevelopments18ASchematicOverviewoftheMovementsinAggregateDemandForeignPolicyandDevelopmentsExchangeRatesCapitalFlowU.S.FiscalPolicyGovernmentSpending&TaxesU.S.MonetaryPolicyMoneySupplyInterestRatesInterestRates,StockPrices,ExchangeRates,ExpectedInflation,EconomicOutlookConsumptionInvestmentNetExportsGovernmentAggregateDemandandIncome19AggregateSupplyAtthelevelofanindividualfirm,supplyissimplythelevelofproductionplannedbythefirmatvariouspricesperunitoveraspecifiedperiodoftimethefirmcomparesthepriceofitsoutputrelativetotheexpectedcostsofproductionrelativepricesplayakeyroleinthefirm’sproductiondecisionsanythingthataltersafirm’srelativepricewillalterthequantityproducedbythefirm20AggregateSupplyThereisadirectrelationshipbetweenpriceandquantitysuppliedButwhataboutasupplycurvefortheaggregateeconomy?Theaggregatesupplycurvefortheeconomyasawholedepictsthelevelofoutputallfirmswillproduceatvariouspricelevelsoveraperiodoftime21AggregateSupplyThereisadirectrelationshipbetweenpriceandquantitysuppliedButwhataboutasupplycurvefortheaggregateeconomy?Theaggregatesupplycurvefortheeconomyasawholedepictsthelevelofoutputallfirmswillproduceatvariouspricelevelsoveraperiodoftimedifferentcurvesfortheshortandlongrun22Short-RunAggregateSupplySupposethattheeconomyisinlong-runequilibriumallpricesandwagesandquantitiesintheeconomyhavefullyadjustedtopreviousshiftsinaggregatedemandorsupplytheconfigurationofinterestrates,exchangerates,expectations,andrelativepriceswillcontinueuntilsomethingelsechanges23Short-RunAggregateSupplyNow,supposethattheFedmakessubstantialopenmarketpurchasesthemoneysupplyrisesandinterestratesfallaggregatedemandrises24Short-RunAggregateSupplyHowwillfirmsrespond?inventorieswillunexpectedlyfallandtherewillbeupwardpressureonthefirms’outputpricesfirmswillincreaseproductiontoincreaseproduction,firmswillneedadditionalinputssincewestartedatfullemployment,thenominalwagewillhavetorise25Short-RunAggregateSupplyThus,theshort-runeffectsoftheincreaseinaggregatedemandwillbeanincreaseinthepricelevelandanincreaseinoutputandemploymentThequantityofgoodsandservicessuppliedriseswhenthepricelevelrisesTheshort-runaggregatesupplycurvewillbeupwardsloping26Short-RunAggregateSupplyRealGDP(inBillions)PriceIndexAggregateSupplyOverallPriceLevel(InBillions)0.95$1,7001.001,5001.051,300$1,300$1,500$1,7001.051.00.95SRASCABADAD

AD

27Long-RunAggregateSupplyAneconomy’snaturallevelofoutputisdeterminedbythequantityandproductivityofitsfactorsofproductioncapitalstocknaturalresourceslaborforceItisthelevelofoutputtowhichaneconomywillmove,givenitsfactorsofproductionandtechnology28DeterminantsoftheNaturalLevelofRealOutputNaturalLevelofRealOutputInstitutionalarrangementsofthelabormarketandotherinputmarketsCapitalStockNaturalresourcesLaborforceTechnologicalknow-how29Long-RunAggregateSupplyTheactuallevelofoutputcanbegreaterthanthenaturalrateintheshortrunfirmsmayrespondtoanincreaseindemandbyoperatingovertimeusingstandbyplantcapacityandemployingmoreworkersthanusualmoreworkersmayacceptjobsbecausetheymistakeariseinnominalwagesforanincreaseintherealwage30Long-RunAggregateSupplyTheactuallevelofoutputcanbelowerthanthenaturalrateintheshortrunfirmsmayrespondtoadecreaseindemandbyleavingplantcapacityidleandlayingworkersoff31Long-RunAggregateSupplyAlevelofoutputthatdiffersfromthenaturalrateisnotsustainableovertimeAneconomyisinlong-runequilibriumonlywhenoutputpricesareconsistentandsustainablerelativetoinputpricesactualvaluesareequaltoexpectedvaluesnounexpectedchangesininventoriesorproduction32Long-RunAggregateSupplySupposethat,duetoanincreaseinaggregatedemand,pricesareexpectedtoriseby10%inthelongrun,inputpriceswillriseproportionatelytomaintaintherealincomesofthesuppliersofthefactorsofproductiontherewillbenoincentiveforfirmstoproducemoreorforworkerstoworkmoreoutputstaysatitsnaturalrate33Long-RunAggregateSupplyThelong-runaggregatesupplycurvewillbeverticalatthenaturalrateofoutput34Long-RunAggregateRealSupplyPriceIndexRealGDP1.00LRASAADAD'B1.0035TheRelationshipbetweentheShortRunandtheLongRunSupposethattheeconomyisinlong-runequilibriumtheactualpricelevelis1.00theeconomyisoperatingatitsnaturalrateofoutput($1,500billion)36ShiftsinShort-Run

AggregateSupplyPriceIndexRealGDP1.00LRASAADSRAS$1,50037TheRelationshipbetweentheShortRunandtheLongRunSupposethereisanunexpectedincreaseinthemoneysupplyaggregatedemandrisesfirmsexperienceunexpecteddeclinesininventoriesandanincreaseinoutputpricefirmsexpandemploymentandproductionthepricelevelrisesto1.05outputrisesto$1,700billion38ShiftsinShort-Run

AggregateSupplyPriceIndexRealGDP1.00LRASAADSRAS$1,500AD’B1.05$1,70039TheRelationshipbetweentheShortRunandtheLongRunTheeconomyisnowinshort-runequilibrium,butnotlong-runequilibriumtheactualpricelevel>theexpectedpricelevelworkershaveactuallyexperiencedadeclineinrealincomeandwillseekanincreaseintheirnominalwagewithemploymentup,labormarketswillbetightandinputpriceswillriseshort-runaggregatesupplywillshiftleft40TheRelationshipbetweentheShortRunandtheLongRunFirmsandinputsuppliershavebasedtheirexpectationsaboutfuturepricesonthecurrentpricelevel(1.05)thisiswhySRASintersectsLRASatapricelevelof1.0541ShiftsinShort-Run

AggregateSupplyPriceIndexRealGDP1.00LRASAADSRAS$1,500AD’B1.05$1,700SRAS’C42TheRelationshipbetweentheShortRunandtheLongRunThehigherinputpricesleadfirmstoproduceless(pointC)Buttheactualpricelevelisstillhigherthantheexpectedpricelevel(atpointC)therewillbeadditionaladjustmentsinpriceexpectations,inputpricesandfirms’productiondecisionstheSRAScurvewillcontinuetoshiftleftuntillong-runequilibriumisestablished43ShiftsinShort-Run

AggregateSupplyPriceIndexRealGDP1.00LRASAADSRAS$1,500AD’B1.05$1,700SRAS’CSRAS’’D1.1044TheRelationshipbetweentheShortRunandtheLongRunTheendresultoftheincreaseindemandisashort-runriseinemployment,output,andthepricelevelalong-runriseinthepricelevelThisisacaseofdemand-pullinflationdemandincreasesand“pullsup”thepricelevel45TheRelationshipbetweentheShortRunandtheLongRunFromapolicymaker’sperspective,theshort-runequilibriumisattractivebutthelong-runsituationismuchlessattractiveifpolicymakersarenearsighted,theymayfocusontheshort-runeffectsofpolicy46SummaryofMajorPointsAggregatedemandisthesumofthequantitiesofgoodsandservicesdemandedbyeachsectoroftheeconomyatvariouspricelevelsquantitydemandedisinverselyrelatedtothepricelevelduetothewealth(realbalance)effectthesubstitution-of-foreign-goodseffecttheconstantnominalincomeeffect47SummaryofMajorPointsThemajorcausesofchangesinaggregatedemandarechangesinU.S.monetaryandfiscalpolicies thesefiscalpolicieshaveapowerfulimpactonspendingplansthroughtheireffectsonthefinancialsystem,ourinternationalcompetitiveness,andexpectations48SummaryofMajorPointsFirms’productiondecisionsareguidedbythepriceoftheiroutputrelativetoexpectedcostsofproductionariseinoutputpricesrelativetoinputpriceswillleadfirmstoexpandproductionafallinoutputpricesrelativ